Cardboard Spawn

You can culture some species of fungi by simply “running” the mycellium on cardboard. Oyster (varieties of the genus Pluerotus), King Stropharia, Wood Blewitt, Nameko among others are amenable to this technique. It is a way of cloning a mushroom by creating the conditions for the mycellium to continue growing the cardboard. as a substrate cardboard is nutrient poor containing mostly cellulose and lignin. This gives the fungus an advantage over competitor organisms.

Ideally you can use the “stem butts” of the mushroom but you can also use mycellium growing on another substrate. for instance directly from an outdoor woodchip bed or grain spawn. Most species that are adaptable to this technique a strong “basal rhizomorphs” visible root-like threads of mycellium (of course this is, in fact, hundreds if not thousands of hyphae banded together). The regenerative power of these species is such that the stem butt will revert to a mycellial vegetative stage if layered on the moist cardboard.

Once the cardboard is fully myceliated is can be used an an inoculum for pasteurised substrate or directly applied to an outdoor bed.

There are two simple methods; layering the cardboard in a plastic container; or making a cardboard “burrito”. Below we detail the Burrito technique but you can simply applying the layer method to a plastic container, just miss out the use of thicker card for the “wrap”.


  • Cardboard
  • hot water


  • Large pot
  •  Plastic bag
  • sharp knife
  • chopping board
  • stapler

Method (Spawn Burrito):

  • soak the cardboard overnight
  • drain, pour boiling water over the cardboard in a pot, cover leave for 30 mins
  • drain thoroughly and cool to below 36c
  • take a thinker piece of the card, this will be your wrap
  • use the softer corrugated pieces, be sure they are not dripping wet
  • take stem butts, thinly slice them and layer them on the corrugated card
  • repeat this layering until you have a size that is easily rolled into a Burrito
  • put the roll of card in a plastic bag, fold the top over once and staple (do not seal completely)
  • incubate at around 20c for week or so; or if you are concerned about potential contamination start the incubation in a refrigerator for 2-3 weeks
  • Once the mycellium has fully run throughout the card you can use it to inoculate a suitable growing substrate or expand further on cardboard.
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